Drivers for animal welfare policies in Europe.

The European region has been, and remains, a global leader in the development of animal welfare policies. The region has a great diversity of cultures and religions, different levels of socio-economic development, and varied legislation, policies and practices. Nevertheless, there are common drivers for animal welfare policy based on a history of animal welfare ethics and obligations to animal users and society in general. A unifying goal of countries in the region is to achieve sustainable compliance with the World Organisation for Animal Health (OIE) standards on animal health and welfare. Ethics isthe overarching driver, supported by the actions of governmental, inter-governmental and non-governmental activities, markets and trade, science and knowledge. Historically, organisations involved in promoting animal welfare have tended to act in isolation. For example, non-governmental organisations (NGOs) have run campaigns to influence retailers and the welfare policies of their farmer suppliers. Increasingly, different organisations with common or complementary goals are working together. For example, competent authorities, inter-governmental bodies and NGOs have combined their efforts to address dog population control across several countries in the region. Also, animal welfare is becoming integrated into the corporate social responsibility targets of private companies. Science and knowledge, as drivers and tools, are assisting with the harmonisation of welfare standards, e.g. by providing a common basis for measuring welfare impacts through animal-based measures and widespread sharing of this information. Current trends suggest that there will be greater collaboration among the organisations driving change, and increasing convergence of animal welfare strategies and welfare assessment tools. The result will be increased harmonisation of animal welfare standards throughout the region.

Calving body condition score affects indicators of health in grazing dairy cows.

The objectives of this study were to determine the effect of calving body condition score (BCS) on cow health during the transition period in a pasture-based dairying system. Feed inputs were managed during the second half of the previous lactation so that BCS differed at drying off (BCS 5.0, 4.0, and 3.0 for high, medium, and low treatments, respectively: a 10-point scale); feed allowance was managed after cows were dried off, such that the BCS differences established during lactation remained at the subsequent calving (BCS 5.5, 4.5, and 3.5; n=20, 18, and 19, for high, medium, and low treatments, respectively). After calving, cows were allocated pasture and pasture silage to ensure grazing residuals >1,600 kg of DM/ha. Milk production was measured weekly; blood was sampled regularly pre- and postpartum to measure indicators of health, and udder and uterine health were evaluated during the 6 wk after calving. Milk weight, fat, protein, and lactose yields, and fat content increased with calving BCS during the first 6 wk of lactation. The effect of calving BCS on the metabolic profile was nonlinear. Before calving, cows in the low group had lower mean plasma ß-hydroxybutyrate and serum Mg concentrations and greater mean serum urea than cows in the medium and high BCS groups, which did not differ from each other. During the 6 wk after calving, cows in the low group had lower serum albumin and fructosamine concentrations than cows in the other 2 treatment groups, whereas cows in the low- and medium-BCS groups had proportionately more polymorphonucleated cells in their uterine secretions at 3 and 5 wk postpartum than high-BCS cows. In comparison, plasma ß-hydroxybutyrate and nonesterified fatty acid concentrations increased linearly in early lactation with calving BCS, consistent with a greater negative energy balance in these cows. Many of the parameters measured did not vary with BCS. The results highlight that calving BCS and, therefore, BCS through early lactation are not effective indicators of functional welfare, with the analyses presented indicating that both low and high BCS at calving will increase the risk of disease: cows in the low group were more prone to reproductive compromise and fatter cows had an increased risk of metabolic diseases. These results are important in defining the welfare consequences of cow BCS.

Behavioral and physiological effects of a short-term feed restriction in lactating dairy cattle with different body condition scores at calving.

Body condition score (BCS) around calving, and the typical BCS loss for up to 100 d after parturition, is associated with both production and reproductive performance of dairy cattle. In addition, there is public concern that thin cows may have impaired welfare, particularly in early lactation where feed demand exceeds pasture growth, and a lag exists between peak milk energy requirements and intake. The aim of this experiment was to determine how BCS at calving influences behavioral and physiological responses to a short-term feed restriction at 47 DIM. Body condition score (on a 10-point scale) at calving was manipulated by modifying the diets in the previous lactation of healthy dairy cattle to generate 3 treatment groups: low BCS (3.4; n=17), medium BCS (4.6; n=18), or high BCS (5.4; n=20). Cows were tested in 4 groups for 8 consecutive days; testing consisted of different levels of feed allocation (d 1 and 2: 100%; d 3 and 4: 75%; d 5: 50%; d 6 to 8: 125%), where 100% was 15kg of DM/cow per day. All BCS groups had similar and marked behavioral and physiological responses to feed restriction. For example, they increased vocalization, time spent eating silage and grazing, aggressive behavior, and fat metabolism (as measured by concentrations of ß-hydroxybutyrate and nonesterified fatty acids), and reduced milk production. Body condition affected some of these responses. Fewer cows with low BCS engaged in aggressive interactions in a feed competition test (trough filled with silage that could be consumed in 15 min) on the first day of feed restriction (low: 32%; medium: 74%; high: 64%; standard error of difference=15.4%). High BCS cows had greater concentrations of ß-hydroxybutyrate and nonesterified fatty acids throughout the experimental period, which suggests more fat mobilization; however, plasma leptin and fecal glucocorticosteroid metabolite concentrations were unaffected by BCS. Whereas cows demonstrated marked responses to feed restriction, the results suggest that a BCS of 3.4, 4.6, or 5.4 in healthy cows at calving does not overwhelmingly influence this response at 47 DIM.

Motivation to obtain a food reward of pregnant ewes in negative energy balance: behavioural, metabolic and endocrine considerations.

Low food availability often coincides with pregnancy in grazing animals. This study investigated how chronic reductions in food intake affected feeding motivation, and metabolic and endocrine parameters in pregnant sheep, which might be indicative of compromised welfare. Ewes with an initial Body Condition Score of 2.7±0.3 (BCS; 0 indicates emaciation and 5 obesity) were fed to attain low (LBC 2.0±0.0,), medium (MBC 2.9±0.1) or high BCS (HBC 3.7±0.1) in the first trimester of pregnancy. A feeding motivation test in which sheep were required to walk a set distance for a palatable food reward was conducted in the second trimester. LBC and MBC ewes consumed more rewards (P=0.001) and displayed a higher expenditure (P=0.02) than HBC ewes, LBC ewes also tended to consume more rewards than MBC ewes (P=0.09). Plasma leptin and glucose concentrations were inversely correlated to expenditure (both P<0.05) and appear to be associated with hunger in sheep. LBC ewes were in negative energy balance, with lower muscle dimensions, plasma glucose, leptin, insulin, cortisol, and insulin-like growth factor-1 concentrations and higher free fatty acids concentrations compared to HBC ewes; metabolic and endocrine parameters of the MBC ewes were intermediate. The high feeding motivation and negative energy balance of low BCS ewes suggested an increased risk of compromised welfare. Imposing even a small cost on a food reward reduced motivation substantially in high BCS ewes (despite high intake when food was freely available). Assessment of a willingness to work for rewards, combined with measures of key metabolic and endocrine parameters, may provide sensitive barometers of welfare in energetically-taxed animals.

Associations among dairy cow body condition and welfare-associated behavioral traits.

Some evidence exists that cow body condition score (BCS) is associated with risks to animal health, and that higher BCS in extensively kept animals provides a buffer against cold conditions or other adverse weather events. Not surprisingly, measures of BCS feature in dairy cattle welfare assessment protocols. However, the degree to which BCS predicts welfare state, particularly in relation to the level of "hunger" experienced, is not well researched. The aim of this study was to examine associations between naturally arising variations in BCS in dairy cattle and time spent engaged in activities used as proxy indicators of hunger. Holstein-Friesian cows (n=113) of either North American or New Zealand ancestry were allocated to 1 of 3 levels of concentrate-feed supplementation (0, 3, or 6 kg of dry matter/d) and also offered pasture in excess of requirements. Body condition score (1 to 10 scale), pasture dry matter intake (DMI), and time budgets for grazing, ruminating, standing, and lying were recorded during early, mid, and late lactation. Body condition score varied over a wide range (2.5 to 8.5) and, within genetic strain and supplementation level, was inversely associated with pasture DMI, rate of DMI, and the proportions of time spent grazing and ruminating. In comparison, variation in BCS (within genetic strain and supplementation level) was directly associated with variations in time spent lying (in late lactation). Nevertheless, pasture DMI and time spent in the key behavioral activities were all within the normal expected limits for pasture-fed dairy cows. Thus, thin cows appeared able to achieve their nutritional requirements. Furthermore, even though thinner cows traded-off a small portion of their lying time in late lactation to forage longer, they still rested for normal periods each day. Based on these results, we found no difference in the welfare status of naturally thin and fat cows when they were offered generous pasture allowances with or without concentrate supplementation. The extent to which this pertains under conditions of persistently low feed allowances that result in reductions in BCS remains to be determined.

Parent and service providers' perceptions regarding the delivery of family-centred paediatric rehabilitation services in a children's hospital.

BACKGROUND: Family-centred service (FCS) provision has long since been acknowledged as the 'best-practice' model within paediatric rehabilitation with numerous reported benefits for both the child and their family. Although family-centred care continues to be investigated worldwide using the Measure of Processes of Care (MPOC) survey, to date only two published studies have been conducted within an Australian context, neither of which were within a hospital setting. As a large number of Australian children attend hospital clinics to receive rehabilitation services, research that investigates FCS within this type of environment is required. This study investigated parent and service providers' perceptions of FCS provision within a large Australian metropolitan children's teaching hospital using the MPOC survey. METHODS: A total of 100 parents/caregivers (34% response rate) whose child had accessed hospital paediatric rehabilitation services over a 12-month period completed the MPOC-20 survey. Thirty-two completed MPOC-SP surveys (80% response rate) were received from the hospital's rehabilitation service providers. Qualitative data were sourced from service providers on their understanding of the term FCS. RESULTS: Parents' perceptions of FCS provision were generally positive, rating Respectful and Supportive Care the highest and Providing General Information the lowest. No significant differences were identified in relation to location of residence, type of disability or number of disabilities per child. Service providers also rated Providing General Information the lowest and felt Treating People Respectfully was strength in the provision of services. Extended responses from service providers indicated that although they possessed a sound understanding of the meaning of FCS, delivering flexible and accessible services and fostering effective communication among all partners were not widely expressed themes. CONCLUSIONS: These results show consistent strengths and weaknesses in FCS provision to children with disabilities and their families and the need to further address the demand for adequate provision of general information.

ZYG-9, a Caenorhabditis elegans protein required for microtubule organization and function, is a component of meiotic and mitotic spindle poles.

We describe the molecular characterization of zyg-9, a maternally acting gene essential for microtubule organization and function in early Caenorhabditis elegans embryos. Defects in zyg-9 mutants suggest that the zyg-9 product functions in the organization of the meiotic spindle and the formation of long microtubules. One-cell zyg-9 embryos exhibit both meiotic and mitotic spindle defects. Meiotic spindles are disorganized, pronuclear migration fails, and the mitotic apparatus forms at the posterior, orients incorrectly, and contains unusually short microtubules. We find that zyg-9 encodes a component of the meiotic and mitotic spindle poles. In addition to the strong staining of spindle poles, we consistently detect staining in the region of the kinetochore microtubules at metaphase and early anaphase in mitotic spindles. The ZYG-9 signal at the mitotic centrosomes is not reduced by nocodazole treatment, indicating that ZYG-9 localization to the mitotic centrosomes is not dependent upon long astral microtubules. Interestingly, in embryos lacking an organized meiotic spindle, produced either by nocodazole treatment or mutations in the mei-1 gene, ZYG-9 forms a halo around the meiotic chromosomes. The protein sequence shows partial similarity to a small set of proteins that also localize to spindle poles, suggesting a common activity of the proteins.

Ultradian, circadian and seasonal rhythms in cortisol secretion and adrenal responsiveness to ACTH and yarding in unrestrained red deer (Cervus elaphus) stags.

Seasonal changes in the activity and responsiveness of the adrenal gland in red deer (Cervus elaphus) stags were quantified by measuring 24 h endogenous cortisol secretory profiles and plasma cortisol responses to either administration of exogenous ACTH or a standardised stressor during November (period of velvet growth), February (pre-rut), April (mid-rut) and July (post-rut) (southern hemisphere) using a remote blood sampling device (DracPac). Ultradian rhythms in the concentration of plasma cortisol were observed resulting from the episodic secretion of cortisol from the adrenal cortex at a mean rate of 0.8 pulses/h. Circadian rhythms in plasma cortisol concentrations were also found in 11 out of the 20 complete 24 h profiles (mean amplitude, 3.8+/-1.4 ng/ml). Seasonal rhythms in mean 24 h plasma cortisol concentrations and cortisol pulse parameters were also observed. Mean 24 h plasma cortisol concentrations were higher in November (12.5+/-1.0 ng/ml) than in February (6.3+/-1.0 ng/ml), April (4.0+/-1.0 ng/ml) or July (4.2+/-1. 0 ng/ml). Cortisol pulse height, nadir and amplitude were all significantly higher in November than at other times of the year (P<0.01). Peak cortisol concentrations following infusion of ACTH(1-24) (0.04 IU kg(-1)) were higher (P<0.05) in November (55.8+/-2.7 ng/ml) and lower (P<0.001) in April (33.7+/-1.8 ng/ml) than those in February and July (48.7+/-2.0 ng/ml and 45.4+/-2.0 ng/ml respectively). The area under the cortisol response curve was significantly smaller (P<0.05) in April (266.6+/-15.3 ng/ml/190 min) than at other times of the year (February, 366.1+/-15.3 ng/ml/190 min; July, 340.7+/-15.3 ng/ml/190 min and November, 387.8+/-21.2 ng/ml/190 min). These data demonstrate that the adrenal gland of the red deer stag exhibits ultradian, circadian and seasonal rhythms in activity, and that its responsiveness to ACTH varies with season. November, a period of reproductive quiescence in the southern hemisphere, with new antler growth and rapid weight gain, is associated with higher mean plasma cortisol concentrations and a greater responsiveness to exogenous ACTH. In contrast, the breeding season is associated with lower adrenal activity and responsiveness.

Duration of cyanide-induced conditioned food aversions in possums.

Learned aversions developed following sublethal ingestion of poisons are reported to be long-lived in many pest species. This study aimed to identify the duration of bait aversions following poisoning with a common poison (cyanide) used for possum control in New Zealand. Groups of possums with bait aversions (following cyanide poisoning) were reexposed to the bait (flavoured food) in a 2-choice test, at intervals of 1, 3, 6, 12, or 24 months. The relative intakes of the bait (used as the measure of bait aversion) did not differ between treatments (0.21, 0.21, 0.27, 0.32, and 0.20) for the 5 groups, respectively. The effect of repeated reexposures to the bait was also tested. The proportion of flavoured food eaten was 0.11, 0.19, 0.23, 0.33, and 0.36 for 1 to 5 reexposures, respectively. There was a significant increase in intake with repeated exposure. Thus, cyanide-induced aversions were strong and lasted for at least 24 months. The aversions weakened over several reexposures to the bait, but only for those individuals that had weaker initial aversions.

Cyanide induced aversions in the possum (Trichosurus vulpecula): effect of route of administration, dose, and formulation.

Possums (Trichosurus vulpecula) are New Zealand's main vertebrate pest. Control practices using poisons are likely to remain the most cost effective methods for the immediate future but poisons may be avoided in the field. A series of experiments were conducted to determine whether cyanide bait avoidance involved conditioned food aversions (CFA) induced by sublethal cyanide ingestion. Food aversions were conditioned in three experiments using intraperitoneal or oral routes of administration with three different cyanide formulations over a range of doses. Across all experiments there was a direct relationship between dose and the proportion of animals developing CFAs. When administered orally, doses greater than 5 mg/kg resulted in more than 50% of surviving animals developing aversions. Route of administration or formulation appeared to have no differential effect on development of CFA. Although there was considerable variation between individuals in the degree of aversion shown this may be one mechanism that could account for poor possum kill rates in some poisoning operations.

Physiological responses of red deer (Cervus elaphus) to conditions experienced during road transport.

Remote heart rate and blood sampling devices were attached to transported red deer stags to assess the effects of several road transport parameters on physiological responses associated with welfare. Stocking density had a significant influence on heart rates and plasma lactate concentrations. Heart rates of deer transported at a high density (0.38 m2 per 84 kg animal) were 10-13% higher than those of deer transported at medium (0.62 m2) or low densities (0.85 m2). Lactate concentrations of animals transported at a high or medium density were 30-40% higher than those of deer transported at a low density. Heart rates of deer transported in the back or middle pens were 7-8% higher than those of deer transported at the front, and lactate concentrations were 30-40% higher. Because elevated heart rates and lactate concentrations are indicative of physiological or psychological challenges, it may be best to transport deer at densities below the currently recommended limit (0.40 m2/100 kg animal) and to keep deer nearer the front of the crate. Although hematocrit, sodium, and cortisol concentrations were not sensitive to variation in stocking density or the animal's position within the crate, cortisol and sodium concentrations increased significantly with time in transit; heart rates and lactate concentrations decreased significantly during the journey. A 2-fold increase in cortisol during the 2-h trip suggests that the length of journeys should be minimized to avoid welfare problems.

Effect of staff debriefing on posttraumatic stress symptoms after assaults by community housing residents.

OBJECTIVE: The study examined the efficacy of critical incident stress debriefing in ameliorating the impact of posttraumatic stress on direct care psychiatric workers after a traumatic event at work. METHODS: Sixty-three direct care workers from two areas in Sydney, Australia, who worked in community residences for persons with developmental and psychiatric disabilities were surveyed about symptoms of intrusive thoughts, avoidance, and hyperarousal one week after they experienced an assault or another type of work-related trauma. Survey respondents included 14 workers who requested and attended a one-session critical incident stress debriefing during the week after the incident, 18 workers from the same area of Sydney who had access to the intervention but chose not to attend, and 31 who worked in an area where the intervention was not available. RESULTS: Sixty-two workers reported symptoms of posttraumatic stress. Lower levels were reported by workers in the area where the intervention was available. When other factors were controlled, the lowest levels of stress were reported by workers to whom the debriefing was available but who chose not to attend. No significant difference in overall stress reduction in the week after the incident was found between the workers who received the intervention and those who did not. CONCLUSIONS: Although critical incident stress debriefing was evaluated positively by the majority of participants, aspects of the intervention such as its timing and the work environment in which it is offered may affect the degree to which participants benefit from it.

Plasma cortisol responses to remote adrenocorticotropic hormone (ACTH) infusion in free-ranging red deer (Cervus elaphus).

A remote infusion and blood collection device (Dracpac) was used on free-ranging red deer stags to deliver i.v. a range of ACTH1-24 doses and collect blood for cortisol determination. In Experiment 1, conducted in September, saline and 1, 4, and 16 IU ACTH/100 kg bodyweight were infused (n = 5-7 per treatment). In Experiment 2 (November), 16 and 64 IU ACTH/100 kg were infused (n = 5 per treatment); and the response of animals to restraint was also assessed (n = 6). Pre-infusion concentrations of plasma cortisol were low (mean 6.5 +/- 1.0 ng/ml), and unaffected by infusion of saline. ACTH significantly elevated plasma cortisol concentrations, with mean peak concentrations occurring 20-40 min postinfusion. Duration of the response was dose dependent, ranging from 80-160 min. With increasing doses of ACTH, maximal peak heights plateaued at approximately 40 and 60 ng/ml in September and November, respectively; whereas the areas under the curves tended to increase. The minimum dose of ACTH that resulted in a maximal peak cortisol response was 4 IU. The maximum peak height of the cortisol response to 16 IU tended to be higher (P < 0.10) in November compared with September, suggesting that adrenal responsiveness may change over this period. The adrenal response to a 16-IU ACTH challenge in Experiment 2 resulted in similar plasma cortisol concentrations to an acute stress event (restraint). Four IU/100 kg ACTH i.v. is recommended as an appropriate dose for ACTH infusion studies in red deer stags. When used in conjunction with the Dracpac technique, it becomes a stress-free, repeatable procedure for assessing aspects of adrenal cortex physiology in free-ranging deer.

Concurrent schedule performance in domestic goats: persistent undermatching.

Performance of nine domestic goats responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. Substantial undermatching of response and time allocation ratios to obtained reinforcement ratios was evident. Post-reinforcement pause time ratios approximately matched obtained reinforcement ratios. Subtracting these times from total time allocation values yielded net time allocation ratios, which undermatched obtained reinforcement ratios to a greater degree than whole-session time allocation ratios. Slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which is similar to previous findings in dairy cows tested under comparable conditions.

Concurrent schedule assessment of food preference in cows.

Six dairy cows (Bos taurus) were trained on several pairs of concurrent variable-interval schedules with different types of food available on each alternative. The required response was a plate press made by the animal's muzzle. Performance generally replicated that found with other species. The generalized matching law accounted for the preference data, showing that food preference could be quantitatively analyzed as a special case of response bias. The preference functions showed that the response- and time-allocation ratios were not as extreme as obtained reinforcement rate ratios (undermatching).

The effect of prepubertal immunization against gonadotropin-releasing hormone on the development of sexual and social behavior of bulls.

To determine the effect of prepubertal immunization against GnRH on the development of sexual and social behavior of Friesian bulls, 90 calves were randomly assigned to five treatments: 1) I2, immunized against GnRH at 2 and boosted at 2.5, 4, and 7.5 mo of age, n = 2 x 10; 2) I4, immunized against GnRH at 4 and boosted at 4.5 and 7.5 mo of age, n = 2 x 10; 3) I7.5, immunized against GnRH at 7.5 and boosted at 8 mo of age n = 2 x 10; 4) S, steers castrated at 2 mo of age, n = 10; and 5) B, intact bulls, n = 2 x 10. Blood samples were collected initially every 2, then every 3 wk. Plasma was analyzed for anti-GnRH titers and plasma testosterone concentration. Sexual and agonistic behavior, male-male mounting, and damage to paddocks was assessed throughout the experiment. All immunized calves developed antibodies against GnRH (32.3 +/- 2.0% bound at a 1:10 plasma:PBS-BSA dilution, 14 d after first boost). Plasma testosterone concentrations were < 1 ng/mL for all immunized animals until 11 mo of age, when they increased to levels found in intact bulls at 14 mo of age. At slaughter, testes and seminal vesicle weights were 38.3 and 31.6% lighter, respectively, for all immunized treatments compared to B. There were no significant differences between I2, I4, and I7.5 in any of the sexual or agonistic behavior tests. Bulls scored higher than steers in all sexual behavior tests. Immunized bulls scored lower than bulls in sexual behavior tests from 10 to 17 mo of age. The proportion of immunized animals that serviced an estrous cow was lower than the proportion of intact bulls at 10, 12.5, 14, and 17 mo of age. Immunized animals scored lower than bulls in bull challenge tests at 8.5, 11.5, 13, 14.5, and 17 mo of age. Paddock damage by animals on the three immunization treatments was lower than that by bulls from 7 to 14.5 mo of age, as were leg were scores (an indicator of male-male mounting behavior) from 9 to 14 mo of age. There was no difference in sexual behavior between immunized bulls (I2, I4, and I7.5) and bulls while held in lairage pens for 16 h before slaughter, but all treatment groups scored higher than steers. There was a similar trend for agonistic behavior, although I4 bulls were no different from steers. Prepubertal immunization against GnRH at 2, 4, and 7.5 mo of age impaired testes function and affected the development of social and sexual behavior of young bulls.

Risk factors associated with bruising in red deer at a commercial slaughter plant.

Bruising of slaughter animals has both economic and welfare implications. In order to identify potential risk factors we surveyed bruising of red deer carcasses from a single Deer Slaughter Plant (DSP) over a three year period. Downgrading due to bruising did not vary between the three years surveyed [1991, n = 21 454, 6.5% downgraded (dg); 1992, n = 22 289, 7.9% dg; 1993, n = 22 262, 6.1% dg]. From an intensive examination of one year's kill (1991) we related the incidence of bruising to various preslaughter transport, seasonal and animal variables. Bruising varied significantly with time of year, hot carcass weight, distance transported, carrier company and carcass fatness. Bruising was related to duration of lairage for some periods of the year which varied with sex. The majority of bruising was on one or other hindquarter implying a consistent cause of the damage. Carcass quality and deer welfare can be best protected by careful driving, by only transporting animals in good condition and avoiding transporting males during the rut.

Transmission of Leptospira interrogans serovar Balcanica infection among socially housed brushtail possums in New Zealand.

Leptospira interrogans serovar balcanica is a potential vector being investigated for spreading a biological control agent among introduced brushtail possums (Trichosurus vulpecula) in New Zealand. As previous studies have shown that possums are unlikely to contract leptospirosis through a contaminated environment alone, the objective was to determine whether L. interrogans serovar balcanica could be transmitted between sexually mature, socially housed possums. Possums were infected experimentally with L. interrogans serovar balcanica and housed in pairs or groups with uninfected possums for either 70 or 140 days, during the breeding or non-breeding seasons. No transmission occurred between any infected and uninfected possums during the non-breeding season. However, transmission occurred between females that had been socially housed in pairs or groups in the breeding season. Mixed sex transmission also occurred in pairs and groups, both from males to females and from females to males. Mixed sex transmission usually occurred rapidly (< 44 days) and was not associated with the production of offspring. No transmission occurred between males during the breeding or the non-breeding seasons. Transmission probably occurs as a result of affiliative or sexual behaviour, but is unlikely to occur through fighting. The social transmission pathways determined in this study suggest that L. interrogans serovar balcanica may have the transmission attributes desired in a vector for biological control.

Leptospirosis in brushtail possums: is Leptospira interrogans serovar balcanica environmentally transmitted?

In New Zealand, the biological control of introduced brushtail possums (Trichosurus vulpecula) may be the only affordable option for achieving a significant long term reduction in pest numbers on a national scale. Leptospira interrogans serovar balcanica is among the potential biocontrol agents and vectors currently being investigated for this purpose. As the transmission pathways of L. interrogans serovar balcanica between possums are poorly understood, the objective of the study was to determine whether infection could result from exposure to contaminated environments. Sixteen individually housed, uninfected possums, in three groups, were regularly exposed over a period of 32 days to contaminated cages or grass enclosures of 16 other experimentally infected possums all shedding leptospires in their urine. None of the 16 challenged possums developed serological evidence of L. interrogans serovar balcancia infection. These results suggest that this organism is unlikely to be transmitted environmentally, supporting previous circumstantial evidence that social contact may be required for transmission of L. interrogans serovar balcanica between possums.